Location system adapted for use in multipath environments
DCFirst Claim
1. A location system for locating objects within a tracking environment using time-of-arrival differentiation for electromagnetic transmissions received at multiple receivers, comprising:
- for each object, a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
an array of receivers distributed within the tracking environment such that a TAG transmission is received by at least three receivers;
each receiver including a time-of-arrival circuit and a data communications controller;
the time-of-arrival circuit is responsive to the arrival of a TAG transmission for providing a TOA count corresponding to the time-of-arrival of the most direct path for such TAG transmission, with the TOA count being synchronized to a system synchronization clock provided to each receiver;
the data communications controller is responsive to the receipt of a TAG transmission for providing a corresponding TOA-detection packet that includes the associated TAG ID and TOA count; and
a location processor for receiving the TOA detection packets, and for determining the location of each TAG, and its associated object, from at least three corresponding TOA-detection packets received from different receivers.
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Accused Products
Abstract
A radiolocation system for multipath environments, such as for tracking objects in a semiconductor fabrication facility (FIGS. 1a-1b), includes an array of receivers (20) distributed within the tracking area, coupled to a system processor (40) over a LAN. A TAG transmitter (30) located with each object transmits, at selected intervals, spread spectrum TAG transmissions including at least a unique TAG ID. In a high resolution embodiment, object location is accomplished by time-of-arrival (TOA) differentiation, with each receiver (FIG. 2b) including a TOA trigger circuit (64) for triggering on arrival of a TAG transmission, and a time base latching circuit (65) for latching the TOA count from an 800 MHz time base counter. In a low resolution embodiment, each receiver of the array is assigned a specific location-area, and receives TAG transmissions almost exclusively from TAGs located in that area, thereby eliminating the need for any time-of-arrival circuitry.
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Citations
54 Claims
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1. A location system for locating objects within a tracking environment using time-of-arrival differentiation for electromagnetic transmissions received at multiple receivers, comprising:
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for each object, a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID; an array of receivers distributed within the tracking environment such that a TAG transmission is received by at least three receivers; each receiver including a time-of-arrival circuit and a data communications controller; the time-of-arrival circuit is responsive to the arrival of a TAG transmission for providing a TOA count corresponding to the time-of-arrival of the most direct path for such TAG transmission, with the TOA count being synchronized to a system synchronization clock provided to each receiver; the data communications controller is responsive to the receipt of a TAG transmission for providing a corresponding TOA-detection packet that includes the associated TAG ID and TOA count; and a location processor for receiving the TOA detection packets, and for determining the location of each TAG, and its associated object, from at least three corresponding TOA-detection packets received from different receivers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. The location system of claim further comprising:
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at least one calibration transmitter, positioned at a known location, for transmitting calibration transmissions receivable by each of the receivers; each receiver being responsive to a calibration transmission for providing a corresponding calibration TOA detection packet, including the associated time-of-arrival TOA count, to the location processor; and the location processor determines calibration coefficients from the calibration TOA detection packets and the known locations of the receivers, and uses those coefficients to calibrate location computations from TOA-detection packets associated with TAG transmissions.
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25. A location system for locating objects within a tracking environment using area-detection by receivers that receive electromagnetic transmissions from assigned areas, comprising:
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for each object, a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID; an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size; each receiver including a data communications controller responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID; and a location processor for receiving the area-detection packets, and for determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A method for locating of objects within a tracking environment using time-of-arrival differentiation for electromagnetic transmissions received at multiple receivers, comprising the steps:
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for each object, transmitting, at selected intervals, TAG transmissions that include a unique TAG ID; providing an array of receivers distributed within the tracking environment such that a TAG transmission is received by at least three receivers; in response to the arrival of a TAG transmission at a receiver, providing a TOA count corresponding to the time-of-arrival of the most direct path for such TAG transmission, with the TOA count being synchronized to a system synchronization clock provided to each receiver; in response to the receipt of a TAG transmission, providing a corresponding TOA-detection packet that includes the associated TAG ID and TOA count; and using the TOA-detection packets, determining the location of each TAG, and its associated object, from at least three corresponding TOA-detection packets received from different receivers. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47)
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48. A method of locating objects within a tracking environment using area-detection by receivers that receive electromagnetic transmissions from assigned areas, comprising:
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for each object, providing a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID; providing an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size; each receiver being responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID; and determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG as represented by the area-detection packet provided by such receiver that received the TAG transmissions. - View Dependent Claims (49, 50, 51, 52, 53, 54)
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Specification